Though typically pale in color, these aquarium fish also can be found with rather beautiful patterns. This is all thanks to very selective breeding of carp with genetic mutations, allowing for diversity. No two koi have the exact same pattern and are popularly known as "swimming jewels" as a result. They can be sold for a very high price, depending on their coloring and pattern. If properly cared for, they can live for over 100 years, making them a staple for outdoor garden ponds.